Welcome to TFF.
Before we suggest possible fish species, most of us here like to know the water parameters. Some fish need harder water than other fish that may need softer water. The GH (general or total hardness) is the most important, then pH. Knowing the KH (carbonate hardness also called Alkalinity) is also worth knowing as it affects pH long-term. These parameters for your source water should be available from your water authority if you are on city water, check their website.
Filtration depends upon the fish species; water flow in the tank results from the filter, so this needs to be suited to the fish. The biological cleaning also needs to be suited to the species and numbers along with the tank size. A filter might be included in the Aqueon ensemble (?). As for heater, this is the most important piece of hardware; a heater failure, whether overheating or failing to heat at all, can wipe out the fish within hours. Again, I do not know if a heater comes with the package. I tend to stay with Eheim Jager heaters, but I am sure there are others that are reliable. For this sized tank, I would use a 200w heater; it should be placed next to the filter return so there is water current to dissipate the heated water.
While waiting for parameter data, I can comment on the mentioned fish. Angelfish and rams are cichlids, and in most cases it is best not to combine cichlids. Males are very territorial, and in this tank a male of either species will consider the tank space "his." The second thing about angelfish is that they are a shoaling species, meaning they live in groups; they develop an hierarchy and need space. At minimum a 4-foot length tank for a group of five; there should never be two, three or four angelfish; this tank is not sufficient space for this. A "pair" which with angelfish means a male/female that have selected each other and bonded, can work, but they will spawn which makes life difficult for other fish in this small a tank. A single angelfish might work, but I do not recommend keeping fish contrary to how nature intended.
As for the ram(s), this species needs more warmth than many tropicals will manage with permanently, so tankmates are not that easy. Cories for example, a substrate fish many aquarists like, need cooler water.
Diamond Tetras will be a bit cramped (it would help to have the tank dimensions, but I am assuming it will be less than 36 inches across) and this is a very active tetra. The high activity level causes other issues, as tankmates have to be accepting of this, and some fish---like any cichlid--will not be.
There is much to consider when selecting fish, but knowing the parameters will get us started.